Electric cable for high frequencies



Aug. 30, 1949. w WESTON 2,480,170

ELECTRIC CABLE FOR HIGH FREQUENCIES Filed Sept. 5, 1946 INVENTOR in? N K. 570

ATTO NEY Patented Aug. 30, 1949 UNITED STATE 2,480,170 ELECTRIC CABLE Foa man FREQUENCIES William Kirby Weston, London, England, assignor to International Standard Electric Corporation, New York, N. Y.

' Application September 5, 1946, Serial at. 095,021

In Great Britain September 7, 1945 This invention relates to concentric conductor electric cables.

In British Application No. 11723/45 there is described a coaxial cable in which the inner-conductor is constructed as a hollow cylinder so. as to function as the outer conductor of an inner coaxial cable. This tubular conductor may be formed by a copper-tape or tapes having abutting longitudinal edges. The problem then arises of holding the tape in circular form.

According to the present invention a tubular inner conductor formed of tape or tapes having abutting longitudinal edges is maintained in spaced relation from its outer conductor by means of spacers of dielectric material, each spacer being formed in two or more portions which when placed together to form a complete washer exert a wedging action upon the tape or tapes forming the conductor so as to hold the edges of the said tape or tapes in abutting relation.

The said discs may be formed of insulating material expanded into a porous honeycomb structure, as described and claimed in British Application No. 20343/44 so that as pointed out therein the pressure upon the inner conductor is more uniformly distributed along the length of the cable, for a given amount of solid insulating material. The portions of the spacers may be held together to exert their wedging action upon the inner conductor either by forming the outer conductor immediately around them, or by extruding a thin walled tube of insulating material around them, or by means of a wrapping of insulating tape.

One embodiment of the invention is shown in the accompanying drawings, in which:

Figure 1 shows a spacing member embracing a hollow inner conductor of a coaxial cable; and

Figure 2 is a view showing how the spacing members may be held upon the inner conductor.

1 Claim. (Cl; 174-28) Referring to the drawings, Figure 1 shows the may be furnished with teeth 3 arranged as described in British Specification No. 476,098 but underlying the innpr sides of the opposite edges. The spacers for locating the inner conductor l concentrically of the outer conductor (not shown) are formed of two portions 4 and 5 which fit together over the folded tape l and abut along lines 6, l which are tangential to the inner conductor. When, therefore the two portions 4 and 5 are held together over the folded tape l by means herein after described, a wedging action is exerted upon the folded tape l which holds the longitudinal edges of the tape together.

In order that this wedging action should be exerted over the greater part or the whole length of the inner conductor l the spacers l, 5 are preferably formed of a thermoplastic material that has been expanded into a porous honeycomb structure.

Figure 2 shows two spacers in position upon the exceed that used in normal air-spaced concentric a low loss thermoplastic material such as a solid polymer of ethylene (polythene).

The twoportions 4, 5 of each spacer are shown in Figure 2 as being held together to exert their wedging action upon the inner conductor I by means of a wrapping of polythene tape 8, 9. Over these tapes is applied the outer conductor (not shown) which'may be of any convenient construction.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

In a coaxial cable of the type that comprises a single metal tape longitudinally folded with edges abutting, constituting a tubular central conductor, an outer conductor arranged concentrically about but in spaced relationship to the central conductor and a plurality of insulating tubular spacers within the outer conductor and surrounding the central conductor to hold the conductors in the desired relationship characterized in that each of said spacers comprises a pair of interengaging elements that, when interengaged, ha.ve 7 REFERENCES CITED an annular cross-sectional outline cut along two 'oppositely directed tangentially extending lines 3 gg g igg of record m the originating at diametrically opposite points on the central opening of the annular area, said ele- 5 UNITED STATES PATENTS ments being maintained in interengagement by Number Name Date tapes wrapped therearound, whereby the longi- 769 639 Sargent Sept 6 1904 tudinal edges of tape constituting the central con- 7993726 Foreman 1905 ductor are Pressed together- 1,9761804 Ringe1 000: 16: 1934 10 2,029,421 Green et al.'- Feb. 4, 1936 WILLIAM KIRBY WESTON- 2,210,400 Fischer et a1; Aug.6,1940 

